DE1758250C - Agent for the desulfurization of iron melts - Google Patents

Description

The invention relates to a means for desulfurizing, for example, in the dicyandiamide production, iron melts based on calcium carbide are produced, in the course of which there are aqueous calcium cyanamide sulphate and another alkaline earth compound. Iron ions treated with carbon dioxide and melted are understood here as pig iron, cast iron and then contain about 70 to 85% calcium carbonate and steel melts. 5 about 8 to 12 ° / ₀ carbon in addition to impurities,

It is known to use calcium carbide alone or with an- in particular iron oxide, aluminum oxide, silicon-

their inorganic compounds such as burnt dioxide.

Lime, sodium fluoride, calcium-silicon, lithium-A content of more than 40 ° / ₀ diamide, although compounds, sodium chloride and sodium carbonate applicable. Here, however, difficulties arise to use the desulfurization of iron melts, »o due to the increasing evolution of gas.
In practice, a specific solution has been found to be The superior properties of the inventive solid desulphurisation agent in the special desulphurisation agent are surprising. B. Pressure desulfurizing agents according to the invention a counter air. Nitrogen, argon, carbon dioxide can be used alone or in a desulfurization mixture that is considerably increased over calcium carbide. In technology, adverse effects are exhibited and, in addition, increasingly higher requirements with regard to a targeted desulfurization effect can be achieved.
low sulfur content of iron. Since the sulfur content of the iron and the desired end can not be achieved with sufficient accuracy or profitability, the desulfurization gains sulfur content. With normal sulfur contents in these melting units more and more important. Iron (about 0.04 to 0.06 ° / ₀₎ satisfies a medium inlet

Desulfurization with calcium carbide alone or with a desulfurizing agent of the order of magnitude

together with compounds such as the above 1.3 kg / t of iron for the removal of 0.010 ° / ₀

as well as the frequently used desulphurisation 25 sulfur. With starting sulfur contents from 0.02 to

using sodium carbonate with respect to the hit - 0.03% / ₀ are on average for the same desulphurisation

Safety and / or economic viability to be desired. Approx. 1.7 kg / t iron required.

left over. Limestone turned out to be compared to others.

inking agents to be largely ineffective. The agent for the melt is expediently the

Finally, the use of 30 was also known to take advantage of the fact that the agent was used in a very fine way

Easily soluble and reactive carbon, distribution is present. It is particularly expedient

7. B. in the form of pitch coke. Blood charcoal, leather charcoal, therefore the addition by blowing in or by

and the like as a deoxidizer together with CaI- stir, in the latter case in the shaking pan or

ciumcarhid as a desulphurizing agent in handling with mechanical stirring devices. Basically it is

depended on cast iron climbers. With regard to the addition, however, to each of the powdery aggregates

Sulphurization of iron melts was possible in this way and can also in the melt?: -

however, compared to the other known desulphurisation units,

no improvement achieved. It is not known what the synergistic point is

There is therefore a need for a reverse effect of diamide lime and calcium carbide.

hesscrtcn desulphurizing agent for iron smelting, 40 is to be added. It is believed, however, that

which does not have these disadvantages and in particular diamide lime cire for desulfurization in particular

the accuracy and profitability improved. has a favorable structure and that in diamide lime

The satisfaction of this need is the task of the finely divided carbon one with the

\ ■> enclosed invention. Desulfurization occurring minor undesirable

According to the invention, this object is compensated for by decarburization and, at the same time, one

(lic development of the agent for desulfurization of desulfurization-demanding reducing conditions

1 isenschmel / cn on the basis of calcium carbide and gen creates.

another alkaline earth compound in such a way that the desulfurizing agent according to the invention

further alkaline earth bond one with 8 to 12 weight - sits one high; Accuracy in its application

per / citt carbon contaminated; as well as this 50 and is also more economical to use because by

111 fine calcium carbonate present in the given state, the smaller amounts of slag

in the form of diamide lime is used, whereby the quantities decrease the iron losses. In addition, .nich

Share of diamide lime 2 to 40 percent by weight, in particular the degree of utilization of the calcium

Fiitschwefclui-iüsmittcls heträpl. Preferably carbide components cheat against the use of

the diamidkii ¹ ''! '. contains H' up to 20 percent by weight. 55 Calcium carbide alone increased significantly.

Among the so-called diamide lime are mixtures.The following example explains the through the

to understand the desulfurizing agent according to the invention obtained essentially from calcium

carbonate and carbon are made. Such mixtures technical progress.

example

A. By comparison, commercial carbide 65 was about 35 tons of pig iron. The desulfurization temperature

at a level of about 30 "/ _D CaC _{2 was} used. was between 1260 and 138O" C. To remove

A precl rock recommended compressed air with 0.01 "/" S was used in the carrier gas.

5 aiii. The (harficnycwichl was in all cases averaging per ton of hot metal blown in.

Pig iron
charge
No. Carbide grain
(mm) S-Go! T ( ⁿ / ") in front of the Ent
sulphurization S content ("/") after the
Desulfurization CaCj utilization factor ( ¹ Vo) 10
11th
12th
13th
14th
15th 0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08 0.043
0.0333
0.029
0.045
0.028
0.055 0.019
0.018
0.018
0.021
0.018
0.040 14.4
10.5
9.9
10, i
7.5
13.2 10.9
(Average value)

B. Furthermore, according to the invention, a mixture of 80 ° / ₀ commercially available carbide with a content of about 80 ° / ₀ CaC, and 2O ⁰ Z ₀ diamide lime was made

with about 75 ° / ₀ CaCO _3, 12% carbon,

Impurities
turns.

(Fe ₂ O ₃ , Al ₂ O ₃ ,

Rest ver

Pig iron batch
No. Grain size of the car
bids
(mm) Grain size of
Diamid lime
(mm) S content ("/") before
desulfurization S content (%,) CaC utilization unit
Degree ("/") 1
2
3
4th
5
6th
7th
8th 0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08
0.06 to 0.08 ΛΛΛΛΛΛΛΛ
oooooooo
ο ο ο ο ο ö ο Ό
Ov Ov Ov Os Ov Ov Ov Ov 0.050
0.037
0.042
0.028
0.058
0.034
0.040
0.056 0.010
0.008
0.014
0.007
0.014
0.016
0.014
0.027 22.8
17.6
20.2
14.8
26.7
26.8
26.0
30.0 23.1
(Average value)

In comparison to experiment A, an improvement was achieved ^{on average above HX) 0} Z _{0 per.}

Claims (2)

Claims: 40 1. Means for desulfurizing iron melts based on calcium carbide and another Alkaline earth bond, marked thereby net that as a further alkaline earth compound one contaminated with 8 to 12 percent by weight carbon, as well as this in finely divided one State present calcium carbonate in the form of diamide lime is used, with the proportion of the diamide lime is 2 to 40 percent by weight of the desulfurizing agent. 2. Means according to claim 1, characterized in that the proportion of diamide lime 10 to 20 percent by weight.